In a process of manufacturing and operating luminaire, the luminaire usually includes a lamp holder portion and a glass bulb portion. Glass acting as an insulation structure is often placed behind a conductive shell of a conventional lamp holder, and then a conductive contact is arranged on the glass insulator. The disadvantage of the lamp holder in this structure lies in that: the glass insulator is required to be fixed to the lamp holder through soldering, which leads to troublesome production, low productivity, and high costs. Therefore, a plastic insulator is used instead of the glass insulator, thereby avoiding the troublesome of soldering. However, the existing lamp holders with use of the plastic insulators are not scientifically reasonable in structural design, and the structure of the lamp holder is prone to be loosened, which poses a negative impact on the reliability of electric conduction and thereby causes users trouble.